JP3470132B2 - Recording / reproducing method for magneto-optical recording medium - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates are those magneto-optical disk, a magneto-optical tape, a recording and reproducing method of the magneto-optical recording medium of the magneto-optical card or the like.

[0002]

2. Description of the Related Art In recent years, a magneto-optical disk has been spotlighted as an external recording medium for a computer. Magneto-optical discs are significantly different from conventional external recording media such as flexible disks or hard disks by creating recording bits in the submicron unit on the medium by applying an external magnetic field and irradiating laser light. It is possible to increase the recording capacity. Therefore, in recent years, the magneto-optical disk has been positioned as the central existence of the memory for storing the increasing data in the rapidly developing multimedia, and there is an increasing demand for its large capacity.

Under such circumstances, practical application of the land / groove recording / reproducing system is being studied in order to improve the recording density. In this method, not only the land area where a recording mark is conventionally recorded, but also a groove area for obtaining a tracking signal sandwiched between adjacent land areas is used as a recording track for recording and reproducing data. It is expected that the recording density of the magneto-optical disk will be greatly improved by utilizing the groove area which has not been used conventionally as a recording area. However, in such a system, since the recording mark formed in the land area and the recording mark formed in the groove area are extremely close to each other, the wavelength of the laser beam currently used (780 n
In m), there was a problem that reproduced signals of adjacent tracks caused crosstalk and could not be reproduced accurately.

On the other hand, a magnetic super resolution medium (MSR (Magnetic Magnetic) which can reproduce a recording mark having a size smaller than the beam spot size.
A reproducing method using an (ally Induced Super Resolution) medium is known. This is a reproducing method in which one recording mark in the beam spot is reproduced while another recording mark is masked to increase the reproduction resolution. In such a reproducing method, a reproducing method called a RAD (Rear Aperture Detection) method for reading a recording mark from a high temperature area using a low temperature area in the beam spot as a mask area is data reading from the high temperature area. Therefore, the recording mark of the adjacent track is not transferred to the reproducing layer, and it is possible to prevent the above-mentioned crosstalk. However, with respect to the signal of the amount of reflected light reflected from the pits of the header portion which is preformat-recorded, crosstalk cannot be avoided because such a magnetic super-resolution effect cannot be obtained, and the ID signal recorded in the header portion is inevitable. However, there is a problem in that the header signal such as the above cannot be accurately reproduced.

Also, if the header signal including the ID signal of the header section is subjected to self-format recording by magneto-optical recording like the data signal of the data section, the problem of crosstalk does not occur. However, when the header section is irradiated with a laser beam having a recording power due to a malfunction of the magneto-optical recording / reproducing apparatus, the data of the header signal is destroyed, which is not practical in terms of reliability.

In order to deal with such a problem, the present inventors have devised a novel magneto-optical recording medium. This magneto-optical recording medium is the M type proposed in Japanese Patent Application No. 6-223277.
This is a combination of an example of the structure of the SR medium and an example of a non-volatile recording medium capable of magneto-optical reproduction proposed in Japanese Patent Application No. 6-223278.

First, the dub proposed in Japanese Patent Application No. 6-223277.
The MSR medium of Rumask will be described. Figure 9 is this M
It is a block diagram of the SR medium, the composition is Gd₃₀Fe₅₅Co
₁₅(Curie temperature: 330 ° C) Regeneration layer 51 (film thickness: 40
nm), composition is Gd_{twenty four}Fe₅₃Co _{twenty three}(Curie temperature: 28
Regeneration assisting layer 52 (film thickness: 25 nm) having a composition of T
b ₂₀Fe₇₈Co₂(Curie temperature: 145 ° C)
Switch layer 53 (film thickness: 10 nm), composition is Tb₁₉Fe₆₇Co₁₄
(Curie temperature: 260 ° C) recording layer 54 (film thickness: 40n
m) is laminated in this order from the substrate side.

Data is recorded on the recording layer 54 in the direction of magnetization, and when the temperature rises due to the irradiation of the reproducing light beam, a part of the temperature in the beam spot is changed to the switching layer 53.
Curie temperature is exceeded. Switch layer
Below the Curie temperature of 53, exchange coupling works so as to align the magnetization direction of the auxiliary reproduction layer 52 with the magnetization direction of the recording layer 54, but this exchange coupling is broken at the portion of the switch layer 53 above the Curie temperature. Therefore, although the reproduction auxiliary layer 52 is aligned with the recording layer 54 at the Curie temperature of the switch layer 53 or lower,
In-plane magnetization occurs in the portion above the Curie temperature.

The reproducing operation will be described with reference to FIG. FIG. 10 is a graph showing the temperature region where the GdFeCo film has perpendicular magnetization with respect to the Gd amount. Solid line a is GdF
The Curie temperature of eCo is shown. The solid line b is G
The perpendicular to in-plane magnetization transition temperature of the dFeCo single layer film, the solid line c is the in-plane to perpendicular magnetization transition temperature of the GdFeCo single layer film, and the broken line d is from the perpendicular of the two-layer film composed of the GdFeCo film and the perpendicular magnetization film. In-plane magnetization transition temperature, broken line e is Gd
The magnetization transition temperatures from the in-plane to the perpendicular of the two-layer film composed of the FeCo film and the perpendicular magnetization film are shown.

Focusing on the composition of a certain Gd amount X1, in-plane magnetization is exhibited even in the temperature region of A in the figure even if it is coupled with the perpendicular magnetization film, and in the temperature region of B in the figure, if it is a single layer film Although it is magnetized, it exhibits perpendicular magnetization when coupled with the perpendicularly magnetized film. In the temperature region of A, the reproducing layer 51 forms a low-temperature mask, and in the temperature region of B, the reproducing auxiliary layer 52 becomes an opening in a portion exhibiting perpendicular magnetization, and the direction of magnetization of the reproducing layer 51 is that of the recording layer 54. Align with the direction of magnetization. In the temperature region of B, the portion where the auxiliary reproduction layer 52 has in-plane magnetization is not coupled with the perpendicular magnetization, and therefore exhibits in-plane magnetization as in the case of the single layer film, and serves as a high temperature mask. As a result, in-plane magnetization masks are formed in both the low temperature region and the high temperature region, and the magnetization of the recording layer 54 is exchanged at the intermediate temperature region (opening) because the switch layer 53 is below the Curie temperature. Switch layer 53 by coupling,
A magneto-optical signal can be obtained by being transferred to the reproducing layer 51 through the reproducing auxiliary layer 52.

Next, a magneto-optically reproducible nonvolatile recording medium proposed in Japanese Patent Application No. 6-223278 will be described. Figure 11
(A) and (b) show the structure of this magneto-optical recording medium, and a volatile magnetic layer 61 capable of magneto-optical recording and reproduction, and a non-volatile magnetic layer exchange-coupled or magneto-statically coupled to this volatile magnetic layer 61. 62
And a laminated structure. The volatile magnetic layer 61 has, for example, a composition of DyFeCo (RE rich) and a film thickness of 50 nm. The nonvolatile magnetic layer 62 has, for example, a composition of TbCo (RE
Rich) and the film thickness is 50 nm. In addition, the non-volatile magnetic layer
The Curie temperature of 62 (300 ° C or higher) is higher than the Curie temperature of the volatile magnetic layer 61 (250 ° C), and the power of the laser light for recording / erasing of the magneto-optical recording / reproducing device that is normally used by the user. Then, the Curie temperature of the volatile magnetic layer 61 is reached, but the Curie temperature of the non-volatile magnetic layer 62 is not reached. Since the magneto-optical recording medium of this example has a recording layer composed of the volatile magnetic layer 61 and the non-volatile magnetic layer 62, the user-side erasable ROM section and the user-side recording, reproducing and erasing It can be used separately from the RAM part capable of performing.

When a media provider such as application software performs ROM recording, laser light having a power higher than that for recording / erasing of a normal magneto-optical recording / reproducing apparatus is irradiated (or at a normal time). The peripheral speed of the magneto-optical recording medium is set lower than that of the above), and heating is performed until the Curie temperature of the nonvolatile magnetic layer 62 of the ROM portion is reached, and data recording is performed while applying an external magnetic field. At this time, the non-volatile magnetic layer 62 of the RAM section is left in a state immediately after the medium is manufactured (so-called as-deposition state) without performing initialization or recording / erasing at all. This As-deposition state is a state in which there is no magnetization aligned in a specific direction, and there is no action of aligning the magnetization of the volatile magnetic layer 61 in a specific direction by magnetic coupling.

With this arrangement, the recording / reproducing of the RAM portion can be freely performed by the usual magneto-optical recording / reproducing apparatus.
Even if the recording / reproducing operation is performed on the ROM portion, the direction of magnetization of the volatile magnetic layer 61 of the ROM portion is aligned with the direction of magnetization of the nonvolatile magnetic layer 62 on which ROM data has been recorded in the process of temperature decrease, so rewriting cannot be performed. Absent. Therefore, this portion becomes a ROM area in which magneto-optical reproduction is possible.

A magneto-optical recording medium capable of performing land-groove recording / reproducing by solving the problem of crosstalk by connecting the above-described two examples of magneto-optical recording media will be described. This magneto-optical recording medium is also proposed in the above-mentioned Japanese Patent Application No. 6-223278. 12 (a) and 12 (b) are diagrams showing the structure of this magneto-optical recording medium, which shows a structure of a magnetic super-resolution medium including a reproducing layer 51, a reproducing auxiliary layer 52, a switch layer 53, and a recording layer 54. The recording layer 54 has a nonvolatile magnetic layer 62 that is exchange-coupled or magnetostatically coupled. The composition, film thickness,
The Curie temperature is the same as that described above with reference to FIGS. 9 and 11, and therefore its explanation is omitted.

A header signal including an ID signal is recorded in advance in the header portion by irradiating a high-power laser beam that exceeds the Curie temperature of the non-volatile magnetic layer 62 (or by lowering the peripheral speed than in normal times). The non-volatile magnetic layer 62 in the data section following the header section is set in the As-deposition state. By doing so, the ID signal recorded in the non-volatile magnetic layer 62 is not destroyed even when the header portion is irradiated with low-power laser light for recording / erasing of a normal magneto-optical recording / reproducing apparatus. Since the ID signal is transferred to the recording layer 54 by exchange coupling or magnetostatic coupling in the process of lowering the temperature, the ID signal is not erased or rewritten. Also, the recording layer
If transferred to 54, the ID signal can also be reproduced by the mask effect according to the above-mentioned principle of supermagnetic resolution, and the crosstalk problem can be solved.

In the recording / reproducing method using the magneto-optical recording medium described above, the header signal is recorded by the non-volatile recording method capable of magneto-optical reproduction and the cross-talk is reproduced by utilizing the super-magnetic resolution effect. Has solved the problem. In addition, reliability can be ensured because of non-volatile recording.

The sector format in this recording / reproducing method is as shown in FIG. Land area 63 and groove area
Independently of each of 64 and 64, the header section 65 and the data section 66 following this form one sector (area surrounded by a broken line) as a recording unit.

Although the recording form in this recording / reproducing method is not limited, when an edge recording method in which the presence or absence of the edge of the recording mark corresponds to "1" or "0" of the recording data is adopted, An example of the relationship among the recorded data, the recording mark 67 and the reproduced waveform is shown in FIGS. 14 (a) and 14 (b).

FIG. 15 shows an example of the structure of a recording system for correctly matching the positions of the edges of the recording marks 67. The pulsing circuit 68 inputs the recording data and the reference clock, generates a pulse signal corresponding to the recording data from the reference clock, and outputs the pulse signal to the laser diode drive circuit 69. The laser diode drive circuit 69 drives and controls the light emission of the laser diode 70 based on this pulse signal. The relationship between the recording data, the emission waveform of the laser diode 70, and the recording mark formed is shown in FIGS. 16A to 16D for each of the four types of recording data.

At the time of reproduction for edge recording, the allowable range of the phase shift between the rising edge signal and the falling edge signal is expanded, and the rising edge rises so that high-accuracy reproduction is possible even in high density recording. Synchronous clock is generated by PLL (Phase Locked Loop) only with edge signal to discriminate data, and falling edge is generated with synchronous clock by PLL only with falling edge signal to discriminate data. After synthesizing the
A synchronous clock is generated by L to perform data discrimination. Such a reproducing method is disclosed by the present inventors in JP-A-6-309808.

FIG. 17 is a block diagram showing the structure of this reproducing system, and FIG. 18 shows the signals, clocks, etc. of the parts marked with a circle in FIG. The reproduced waveform detected by the optical system is input to the edge detection unit 71 and the slice level setting unit 72. The slice level setting unit 72 sets the level at the midpoint of the reproduced waveform as the slice level for binarization and outputs it to the edge detection unit 71. The edge detection unit 71 binarizes the reproduced waveform at the slice level, separates the rising edge and the falling edge of the binarized signal to obtain the rising edge signal and the falling edge signal, and outputs the rising edge signal. Is output to the data discriminating unit 73, the PLL circuit 74, and the OR circuit 78, and the falling edge signal is output to the data discriminating unit 75, the PLL circuit 76, and the OR circuit 78.

The synchronous clock generated by the PLL circuit 74 in synchronization with the rising edge signal is supplied to the data discriminating unit 73. The data discriminating unit 73 outputs a signal from which noise jitter is removed by synchronizing the rising edge signal with this synchronizing clock to the OR circuit 77. Similarly, the synchronous clock generated by the PLL circuit 76 in synchronization with the falling edge signal is supplied to the data discriminating unit 75. The data discriminating unit 75 outputs a signal from which noise jitter is removed by synchronizing the falling edge signal with this synchronizing clock to the OR circuit 77. O
The R circuit 77 obtains the logical sum of both input signals to determine the data discrimination unit.
Output to 79. On the other hand, the OR circuit 78 obtains the logical sum of the rising edge signal and the falling edge signal from the edge detector 71 and outputs the logical sum to the PLL circuit 80. PLL circuit 80
The synchronous clock generated in synchronization with the output signal from the OR circuit 78 is supplied to the data discriminating unit 79. Data discriminator
Reference numeral 79 synchronizes the output signal from the OR circuit 77 with this synchronizing clock to obtain a reproduction signal from which noise jitter has been removed, and outputs the reproduction signal as reproduction data.

FIG. 19 shows a structural example of an optical system for such a magneto-optical recording medium. In the figure, 100 is a magneto-optical recording medium having the above-described configuration, and 81 is a laser diode that emits a light beam. Laser diode
On the exit side of 81, a collimator lens 82 for collimating a light beam and a beam shaping prism 83, a beam splitter 84 for transmitting or reflecting the light beam, and an objective lens 85 whose position is controlled by an actuator (not shown) are arranged in this order. Has been done.

On the reflection side of the beam splitter 84, a beam splitter 86 that transmits or reflects a light beam, a half-wave plate 87 that rotates a deflection surface of the light beam, and an incident light beam are separated into a horizontal component and a vertical component. Polarizing beam splitter 88
Are arranged in this order. Polarizing beam splitter 88
The photodetectors 89, 90 for detecting the horizontal and vertical components of the output light are provided on the output side of the photodetectors 89, 90.
An amplifier 91 for obtaining the sum or the difference between the detection signals of the two photodetectors 89 and 90 and amplifying them is connected to the. On the reflection side of the beam splitter 86, a condenser lens that condenses the incident light beam.
92, a cylindrical lens 93, and a quadrant photodetector 94 for detecting the intensity of the incident light beam are arranged in this order.
In the half-wave plate 87, the polarization beam splitter 88, and the photodetectors 89 and 90 described above, a magneto-optical signal detection system that detects a change in the polarization angle of the reflected light caused by the magneto-optical effect due to the difference in the magnetization direction is used. The condensing lens 92, the cylindrical lens 93, and the four-division photodetector 94 configured as described above constitute a light spot control signal detection system that performs focusing control and tracking control of the spot of the light beam.

The light beam emitted from the laser diode 81 is collimated by the collimator lens 82 and the beam shaping prism 83, and then focused on the magneto-optical recording medium 100 via the objective lens 85. The reflected light from the magneto-optical recording medium 100 is reflected by the beam splitter 84, is further divided into two directions by the beam splitter 86, and is guided to the magneto-optical signal detection system and the light spot control signal detection system.

In the magneto-optical signal detection system, the deflection angle of the reflected light is approximately equal to that of the polarization beam splitter 88 by the half-wave plate 87.
The polarization beam splitter 88 separates the horizontal component and the vertical component of the reflected light beam at 45 °, and the photodetectors 89 and 90 convert the components into electrical signals. Then, in accordance with the difference output of both electric signals from the amplifier 91, the magneto-optical recording medium 100
A magneto-optical reproduction waveform that is inverted according to the direction of the upper magnetization is obtained. Further, according to the sum output of both electric signals from the amplifier 91, a light quantity change waveform due to prepits on the magneto-optical recording medium 100 is obtained. On the other hand, in the light spot control signal detection system, based on the detection signal of the four-division photodetector 94, focusing control,
Performs tracking control.

[0027]

The above-described magneto-optical recording medium is excellent in that the problem of crosstalk can be solved and land / groove recording / reproducing can be performed with high accuracy. However, since the header signal including the ID signal is not preformat-recorded and the header signal is not recorded at the time of manufacturing the medium, it is necessary to record the header signal for every sector after manufacturing the medium. However, it takes a long time to form the format of the medium, and the problem remains in terms of mass productivity.

In the above-described magneto-optical recording medium for land / groove recording, track density (density in the radial direction)
However, since the linear density (density in the circumferential direction) does not change, there is a problem that the transfer rate does not accompany the increase in recording capacity.

The present invention has been made in view of such circumstances, and a sector is formed over the adjacent land area and groove area, and the header signal of the sector is recorded only in one of the land area and the groove area. by, you can accurately reproduce the header portion without crosstalk occurs, moreover an object of the invention to provide a recording and reproducing method of the magneto-optical recording medium body thereby improving the mass productivity.

Data recording is performed so that "1" of the recording data is alternately associated with the edge of the recording mark in the land area and the edge of the recording mark in the groove area. Data can be reproduced even if only one of them has a header part.
Moreover an object of the invention to provide a recording and reproducing method of the magneto-optical recording medium body thereby improving the without transfer rate being accompanied by signal degradation.

[0031]

A recording / reproducing method for a magneto-optical recording medium according to a first aspect of the present invention is a land area of the magneto-optical recording medium.
The land and groove areas are used for data recording and reproduction.
A method of recording / reproducing a magneto-optical recording medium for recording / reproducing a lube.
In this case, one sector, which is a data recording unit, is adjacent to each other.
Formed over the land area and groove area.
The data section following the header section in the one sector
As a recording method, the presence or absence of the edge of the recording mark is recorded.
Uses edge recording method corresponding to "1" and "0" of data
The land area adjacent to the recorded data "1"
The edges of the recording marks and the groove areas correspond alternately.
The data is recorded as described above .

[0032]

[0033]

[0034]

According to a second aspect of the present invention, there is provided a recording / reproducing method for a magneto-optical recording medium according to the first aspect, wherein the adjacent land area and groove area are irradiated with independent light beams when the recording data is reproduced. To do.

According to a third aspect of the present invention, there is provided a recording / reproducing method for a magneto-optical recording medium according to the second aspect , in which reflected beams from adjacent land regions and groove regions are overlapped and received, and the received light waveforms are set to two threshold levels. The recording data is reproduced by slicing at.

[0037]

1 is a diagram showing a sector format in the magneto-optical recording medium of the present invention. As shown in FIG. 1, according to the present invention, the land area 1 and the groove area 2 adjacent to each other constitute one sector (a portion surrounded by a broken line in FIG. 1), and a data portion following the header portion 3 is formed. Since 4 is dispersed in the land area 1 and the groove area 2, the header portion 3 may be formed in only one of the land area 1 and the groove area 2 (in the example shown in FIG. 1, only the land area 1). . Therefore, even if the header signal of the header section 3 is preformat-recorded, the distance between adjacent recording tracks is the distance between the adjacent land areas 1 (or the distance between the adjacent groove areas 2). It is longer than the magneto-optical recording medium for groove recording, and crosstalk does not occur.

FIGS. 2A and 2B are diagrams showing an example of the relationship between the recording data, the recording mark and the reproduction waveform in the edge recording performed in the recording / reproducing method of the magneto-optical recording medium of the present invention. As shown in FIG. 2A, in the present invention, recording is performed so that the edge of the recording mark 50 in the land area 1 and the edge of the recording mark 50 in the groove area 2 alternately correspond to each "1" of the recording data. I do. By doing so, the length L1 of the recording mark 50 in the land area 1 or the groove area 2 becomes equal to the recording mark 67 in the land area 63 (or groove area 64) of the conventional example shown in FIG.
If the length is the same as the length L2, as can be seen by comparing FIGS. 2 (a) and 14 (a), the linear density is doubled in the present invention as compared with the conventional land groove recording. The transfer rate is also doubled.

Further, according to the present invention, the reproducing light beams independent of each other are applied to the land area 1 and the groove area 2, and the reflected light for each light beam is superimposed to form a reproducing waveform. First slice level and second
Data is detected by slicing at two slice levels of the slice level. If the powers of the two reproduction light beams are substantially the same, the level difference between the level midpoint and the peak (A1 in FIG. 2B) and the level difference between the level midpoint and the bottom (FIG. 2) in the superimposed reproduction waveforms. Since (A2) in (b) is substantially equal to the amplitude of the reproduced waveform in the conventional example (A3 in FIG. 14B), signal deterioration does not occur in the present invention.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments.

As shown in FIG. 1, the sector format in the magneto-optical recording medium of the present invention is such that the header portion 3 formed only in the land area 1 and subsequently the land area 1 and the groove area 2 are dispersed. One sector is formed from the data section 4. The header signal including the ID signal is preformat-recorded in the header portion 3 formed only in the land area 1.

In the recording / reproducing method of the present invention, FIG.
As shown in (a), "1" of the recording data is first on the edge of the recording mark 50 in the land area 1, and "1" of the next recording data is on the edge of the recording mark 50 in the groove area 2, and "1" of recorded data is the recording mark of land area 1
At the edge of 50, the next recording data “1” is at the edge of the recording mark 50 in the groove area 2, and the recording data “1” is at the recording mark of the land area 1 and the groove area 2.
Alternate to 50 edges. Therefore, according to the present invention, as in the above-described conventional example of land / groove recording, the track density is doubled as compared with the conventional example of non-land / groove recording. Since the linear density is doubled as compared with, the transfer rate can be doubled.

Next, FIG. 3 shows the configuration of the optical system in the recording / reproducing method of the present invention. In FIG. 3, 10 is a magneto-optical recording medium, and 5 is a laser diode for emitting a light beam. The laser diode 5 has a structure in which two laser diode elements are incorporated in a package, and emits two light beams of a laser beam for the land area 1 and a laser beam for the groove area 2. On the emission side of the laser diode 5, a collimating lens 6 that collimates a light beam
A beam shaping prism 7, a beam splitter 8 that transmits or reflects a light beam, and an objective lens 9 whose position is controlled by an actuator (not shown) are arranged in this order. Then, the light beams from both laser diode elements of the laser diode 5 are focused on the land area 1 and the groove area 2 which are adjacent to each other on the magneto-optical recording medium 10. The polarization directions of the two light beams are the same.

On the reflection side of the beam splitter 8, a beam splitter 11 that transmits or reflects a light beam, a half-wave plate 12 that rotates a deflection surface of the light beam, and an incident light beam are separated into a horizontal component and a vertical component. Polarizing beam splitter 13
Are arranged in this order. Polarizing beam splitter 13
The photodetectors 14 and 15 for detecting the horizontal and vertical components of the output light are provided on the emission side of the photodetectors 14 and 15, respectively.
An amplifier 16 for obtaining the sum or difference of the detection signals of both photodetectors 14 and 15 and amplifying the same is connected to the. On the reflection side of the beam splitter 11, a condenser lens that condenses the incident light beam
17, a cylindrical lens 18, and a four-division photodetector 19 for detecting the intensity of the incident light beam are arranged in this order.
In the half-wave plate 12, the polarization beam splitter 13, and the photodetectors 14 and 15 described above, a magneto-optical signal detection system that detects a change in the polarization angle of the reflected light caused by the magneto-optical effect due to the difference in the magnetization direction is used. A light spot control signal detection system for performing focusing control and tracking control of the spot of the light beam is configured by the condenser lens 17, the cylindrical lens 18, and the four-division photodetector 19 described above.

The two light beams emitted from the laser diode 5 are collimated by the collimator lens 6 and the beam shaping prism 7, and then the adjacent land areas 1 of the magneto-optical recording medium 10 are passed through the objective lens 9. And the groove area 2 are focused respectively. Each reflected light from the magneto-optical recording medium 10 is reflected by the beam splitter 8 and then further divided into two directions by the beam splitter 11, and is guided to the magneto-optical signal detection system and the light spot control signal detection system. .

In the magneto-optical signal detection system, the deflection angle of the reflected light is approximately equal to that of the polarization beam splitter 13 by the half-wave plate 12.
The polarization beam splitter 13 separates the horizontal component and the vertical component of each reflected light beam at 45 °, and the photodetectors 14 and 15 convert the components into electrical signals. And the amplifier 16
According to the difference output of both electric signals from the magneto-optical recording medium 10
A magneto-optical reproduction waveform that is inverted according to the direction of the upper magnetization is obtained. Further, according to the sum output of both electric signals from the amplifier 16, a light quantity change waveform due to prepits on the magneto-optical recording medium 10 is obtained. On the other hand, in the light spot control signal detection system, focusing control and tracking control are performed based on the detection signal of the four-division photodetector 19.

In the present invention, two reflected light beams from the adjacent land region 1 and groove region 2 of the magneto-optical recording medium 10 are introduced into the same photodetectors 14 and 15 through the same optical path, and therefore, it is obtained. The reproduction waveform is a superposition of the reproduction waveforms of the reflected light beams (see FIG. 2B). From the superimposed reproduced waveform, the land area 1 and the groove area 2
The rising and falling edges of each edge must be detected. Details of this reproducing operation will be described later.

On the other hand, even in the light spot control signal detection system, 4
Two reflected light beams are superposed and input to the split photodetector 19. Even with two reflected light beams, the focusing signal can be detected without any problem. However, regarding the tracking signal, the tracking signal by the reflected light beam from the land area 1 and the tracking signal by the reflected light beam from the groove area 2 cancel each other, so that the tracking signal can be detected stably.
Tracking control for the power of one light beam 0.1 ~
It is better to keep a difference of about 0.3 mW.

Next, the structure and operation of the recording system of the present invention will be described. FIG. 4 is a block diagram of the recording system used in the present invention, FIG. 5 is an internal block diagram of the data separation unit 20 shown in FIG. 4, and FIG. 6 is a signal waveform diagram of a portion indicated by a circle in FIGS. . As described above, in the present invention, the two laser diode elements of the laser diode 5 irradiate the land region 1 and the groove region 2 with light beams, respectively, for recording / recording.
Playback is performed, so to control each light emitting system, 2
Two control systems are provided. A first pulsing circuit 21 for inputting the recording data and the reference clock for the land area 1 to generate a pulse signal according to the recording data, a first drive circuit 22 for controlling light emission based on the pulse signal, and a land The first laser diode element 23 that emits the light beam to the region 1 constitutes a control system for the land region 1. On the other hand, a second pulsing circuit 24 for inputting the recording data and the reference clock for the groove area 2 to generate a pulse signal according to the recording data, and a second driving circuit 25 for controlling light emission based on the pulse signal. , With the second laser diode element 26 that emits a light beam to the groove region 2,
A control system for the groove area 2 is configured.

Further, a data separating section 20 for separating the designated recording data into recording data for the land area 1 and recording data for the groove area 2 is provided. As shown in FIG. 5, the data separation section 20 receives the D-FF 27 to which the recording data is input and outputs the recording data for the land area 1 to the first pulsing circuit 21, and the recording data “1”. NOT circuit 28 which inverts and outputs the input record data every time
And the output of the NOT circuit 28 to input the recording data for the groove area 2 to the second pulsing circuit 24.
And have. Then, the light emission of each of the first laser diode element 23 and the second laser diode element 26 is controlled based on the output which is alternately inverted every "1" of the recording data.

Next, the structure and operation of the reproducing system according to the present invention will be described. FIG. 7 is a configuration diagram of a reproducing system used in the present invention, and FIG. 8 is a signal waveform diagram of a portion indicated by a circle in FIG. The concept and principle of edge detection in the present invention are the same as those in the conventional example described above. However, in the present invention, as described above, two adjacent land regions 1 and two groove regions 2 are used.
Since the reproduced waveform can be obtained by superimposing the two reflected light beams,
The rising edge and the falling edge of this reproduced waveform are detected at two slice levels, and the rising edge and the rising edge are detected.
A rising edge signal and a falling edge signal are obtained by taking the logical sum of the edge signals at each falling edge.

The reproduced waveform obtained by the optical system is input to the first edge detecting section 31, the first slice level setting section 32, the second edge detecting section 33 and the second slice level setting section 34. When the powers of the two reproduction light beams are substantially the same, the first slice level setting unit 32 determines that the peak of the reproduction waveform is 1/4.
The level is set as the first slice level for binarization and output to the first edge detection unit 31. The second slice level setting unit 34 sets a level of about 1/4 from the bottom of the reproduced waveform as the second slice level for binarization and outputs it to the second edge detection unit 33.

The first edge detector 31 binarizes the reproduced waveform at the first slice level, separates the rising edge and the falling edge of the binarized signal, and separates the rising edge signal and the falling edge. A signal is obtained, a rising edge signal is output to the OR circuit 35, and a falling edge signal is output to the OR circuit 36. Similarly, the second edge detection unit 33 binarizes the reproduced waveform at the second slice level, separates the rising edge and the falling edge of the binarized signal, and separates the rising edge signal and the falling edge. A signal is obtained, a rising edge signal is output to the OR circuit 35, and a falling edge signal is output to the OR circuit 36.

The OR circuit 35 obtains the logical sum of the two rising edge signals that are input, and outputs the data discriminator 37 and PL.
It outputs to the L circuit 38 and the OR circuit 42. On the other hand, the OR circuit 36
Outputs the logical sum of the two falling edge signals input to the data discriminating unit 39, the PLL circuit 40, and the OR circuit 42. The synchronous clock generated by the PLL circuit 38 in synchronization with the rising edge signal is supplied to the data discriminating unit 37. The data discriminating unit 37 outputs a signal from which noise jitter is removed by synchronizing the rising edge signal with this synchronizing clock to the OR circuit 41. Similarly, the synchronous clock generated by the PLL circuit 40 in synchronization with the falling edge signal is supplied to the data discriminating unit 39. The data discriminating unit 39 outputs a signal from which the noise jitter is removed by synchronizing the falling edge signal with this synchronizing clock to the OR circuit 41. O
The R circuit 41 calculates the logical sum of both input signals and outputs the logical sum to the data discriminating unit 43. On the other hand, the OR circuit 42 calculates the logical sum of the output signals of the OR circuit 35 and the OR circuit 36 and outputs the logical sum to the PLL circuit 44. A synchronous clock generated by the PLL circuit 44 in synchronization with the OR signal from the OR circuit 42 is supplied to the data discriminating unit 43. The data discriminating unit 43 synchronizes the logical sum signal from the OR circuit 77 with this synchronizing clock to obtain a reproduction signal from which noise jitter is removed, and outputs the reproduction signal as reproduction data.

Even in the optical disk using only the land area or only the groove area as the recording track, the edges of the recording marks alternately correspond to the adjacent recording tracks according to the data "1" as in the present invention. It goes without saying that it is possible to record and reproduce the information as described above.

[0056]

As described above, according to the present invention, the sector is formed over the adjacent land area and groove area, and the header signal of the sector is recorded in only one of the land area and the groove area. Therefore, it is possible to accurately reproduce the header portion without causing crosstalk, and it is possible to form the header portion in the pre-format even in the case of land groove recording. Mass productivity can be improved.

Further, since data recording is performed so that "1" of the recording data is made to correspond alternately to the edge of the recording mark in the land area and the edge of the recording mark in the groove area, there is no signal deterioration, In addition to the track density, the linear density can be doubled, and the transfer speed can be improved corresponding to the increase of the recording capacity in the land / groove recording.

[Brief description of drawings]

FIG. 1 is a sector format diagram in a magneto-optical recording medium of the present invention.

FIG. 2 is a diagram showing the relationship among recording data, recording marks, and reproduced waveforms in edge recording of the present invention.

FIG. 3 is a configuration diagram of an optical system used in the present invention.

FIG. 4 is a configuration diagram of a recording system used in the present invention.

FIG. 5 is an internal configuration diagram of a data separation unit in the recording system of the present invention.

FIG. 6 is a timing chart in the recording system used in the present invention.

FIG. 7 is a configuration diagram of a reproduction system used in the present invention.

FIG. 8 is a timing chart in the reproducing system used in the present invention.

FIG. 9 is a configuration diagram of a magnetic super-resolution medium.

FIG. 10 is a diagram showing a magnetization state of a GdFeCo film.

FIG. 11 is a configuration diagram of a magneto-optical recording medium capable of ROM recording.

FIG. 12 is a configuration diagram of a magnetic super resolution medium capable of ROM recording.

FIG. 13 is a sector format diagram in a conventional magneto-optical recording medium.

FIG. 14 is a diagram showing a relationship among recording data, recording marks, and reproduced waveforms in conventional edge recording.

FIG. 15 is a configuration diagram of a recording system used in a conventional example.

FIG. 16 is a diagram showing a relationship among recording data, laser diode emission waveforms, and recording marks in edge recording.

FIG. 17 is a configuration diagram of a reproduction system used in a conventional example.

FIG. 18 is a timing chart in the reproducing system used in the conventional example.

FIG. 19 is a configuration diagram of an optical system used in a conventional example.

[Explanation of symbols]

1 land area 2 groove area 3 header 4 data section 5 Laser diode 10 Magneto-optical recording medium 20 Data separation unit 21 First pulse circuit 22 First drive circuit 23 First laser diode element 24 Second pulse conversion circuit 25 Second drive circuit 26 Second laser diode element 50 record mark

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G11B 11/105

Claims (3)

(57) [Claims] 1. A land area and a glue of a magneto-optical recording medium.
Land groove recording that uses the groove area for recording and reproducing data
In a recording / reproducing method of a magneto-optical recording medium for reproducing,
Land area that adjoins one sector that is the recording unit of data
Formed over the area and the groove area,
Method for recording in the data section following the header section in a sector
As for the presence or absence of the edge of the recording mark,
Recording using the edge recording method corresponding to "1" and "0"
Land area and groove adjacent to "1" of data
Design so that the edges of the recording mark and the area correspond alternately.
The recording of a magneto-optical recording medium characterized by recording data
Recording and playback method. 2. A land adjacent to one another when reproducing recorded data.
Irradiating the area and the groove area with independent light beams
A recording / reproducing method for the magneto-optical recording medium according to claim 1 . 3. The land area and groove area adjacent to each other
The reflected beams from each area are received in a superimposed manner and the received light waveform
Of recorded data by slicing at two threshold levels
Recording and reproducing method of the magneto-optical recording medium according to claim 2, wherein the performing.